Fourier transform spectrometer having high and low gain channels

Abstract

A high S/N Fourier transform spectrometer with low A/D converter noise, comprising a light receiving device; a low gain channel and a high gain channel which convert to and retain as digital signals the output from the light receiving device; and a computation control unit which determines a correlation equation between the low gain and high gain channels and substitutes the low gain channel output converted using the correlation equation for the saturated portion of the high gain channel output.

What is claimed is: 
     
       1. A Fourier transform spectrometer comprising: optical detector means for receiving an interference light;   low gain channel means and high gain channel means for converting and retaining an output from said optical detector means; and   computation control means for determining an equation for correlation between said low gain channel means and said high gain channel means, and for substituting output from said low gain channel means as converted with said equation for correlation for a saturated portion of an output from said high gain channel means.   
     
     
       2. The spectrometer of claim 1, wherein said equation for correlation is determined at any time. 
     
     
       3. The spectrometer of claim 1, further comprising means for optimizing gain of said high gain channel means so that value of S/N is maximized. 
     
     
       4. The spectrometer of claim 2, further comprising means for optimizing gain of said high gain channel means so that value of S/N is maximized. 
     
     
       5. A Fourier transform spectrometer comprising: optical detector means for receiving an interference light;   low gain channel means and high gain channel means for converting and retaining an output from said optical detector means; and   computation control means for determing a transfer function between said high gain channel means and said low gain channel means, and for adjusting a phase of output from said low gain channel means based on said transfer function.   
     
     
       6. The spectrometer of claim 5, wherein said transfer function is determined at any time. 
     
     
       7. The spectrometer of claim 5, further comprising means for optimizing gain of said high gain channel means so that value of S/N is maximized. 
     
     
       8. The spectrometer of claim 6, further comprising means for optimizing gain of said high gain channel means so that value of S/N is maximized.